mcdonald (pam78654) – HW 6B: Thermodynamics – laude – (89 560) 1This print-out should have 21 questions.Multiple-choice questions may continue o nthe next column or page – find all choicesbefore answering.001 10.0 pointsCalculate the change in enthalpy for thecombustion of graphite using the data below.H2(g) +12O2(g) ←→ H2O(l)∆H = −285.83 kJ · mol−1CO2(g) + 2H2O(l) ←→ CH4(g) + 2O2(g)∆H = 882.00 kJ · mol−1Cgraphite(s) + 2H2(g) ←→ CH4(g)∆H = −74.87 kJ · mol−1Cgraphite(s) + O2(g) ←→ CO2(g)∆H = ?1. −385.21 kJ · mol−12. −515.87 kJ · mol−13. 521.30 kJ · mol−14. −230.04 kJ · mol−15. 235.47 kJ · mol−1002 10.0 pointsWhich of the reactions below will likelyhave the largest increase in entropy (∆Srxn)?1. C5H12(l) + 8O2(g) →6H2O(g) + 5CO2(g)2. N2H4(g) + H2(g) → 2NH3(g)3. Na+(g) + Cl−(g) → NaCl(s)4. S3(g) + 9F2(g) → 3SF6(g)5. 2CH4(g) + 2O3(g) →4H2O(g) + 2CO(g)003 10.0 pointsWhat is true about the first law of thermody-namics?1. ∆Euniv< 02. ∆Euniv= 03. ∆Esys= 04. ∆Esys< 05. ∆Esys> 06. ∆Euniv> 0004 10.0 pointsWhich ofO2(g), O2(ℓ), H2(g), H2(ℓ), H2O(g), H2O(ℓ)have a heat of formation equal to zero?1. O2(g), O2(ℓ), H2(g), H2(ℓ), H2O(g),H2O(ℓ)2. O2(g), O2(ℓ), H2(g), H2(ℓ)3. All of them, but only at absolute zero4. O2(g), H2(g)5. O2(g), H2(g), H2O(g)005 10.0 pointsIf 25.0 g of water at 100.0◦C are mixed with15.0 g of water at 40.0◦C, what t emperaturewill the 40.0 g of combined water be at oncethey reach equilibrium?1. 70.0◦C2. 77.5◦C3. 60.0◦C4. 62.5◦Cmcdonald (pam78654) – HW 6B: Thermodynamics – laude – (89 560) 2006 10.0 pointsCalculate the reaction enthalpy for the forma-tion2 Al(s) + 3 Cl2(g) −→ 2 AlCl3(s) ,of anhydrous aluminum chloride using thedata2 Al(s) + 6 HCl(aq) −→2 AlCl3(aq) + 3 H2(g)∆H◦= −1049 kJHCl(g) −→ HCl(aq) ∆H◦= −74.8 kJH2(g) + Cl2(g) −→ 2 HCl(g) ∆H◦= −185 kJAlCl3(s) −→ AlCl3(aq) ∆H◦= −323 kJ1. −1883.5 kJ2. −1100.36 kJ3. −1225.7 kJ4. −1502.4 kJ5. −1450.85 kJ6. −1406.8 kJ7. −1826.2 kJ007 10.0 pointsThe pressure-volume work done by an idealgaseous system at constant volume is1. −∆PP2. zero3. −∆E4. q5. −V ∆P008 10.0 pointsA CD player and its battery together do 500kJ of work, and the batt ery also releases 250kJ of energy as heat and the CD player re-leases 50 k J as heat due to friction from spin-ning. What is the change in i nternal energy ofthe system, with the system regarded as thebattery and CD player together?1. −700 kJ2. −200 kJ3. −800 kJ4. −750 kJ5. +200 kJ009 10.0 pointsWhich of the following would probably have apositive ∆S value?1. He(g, 2 atm) → He(g, 10 atm)2. H2(g) + I2(s) → 2 HI(g)3. 2 NO2(g) → N2O4(g)4. O2(g) → O2(aq)5. 2 Ag(s) + Br2(ℓ) → 2 AgBr(s)010 10.0 pointsWhich of the following statements is alwaystrue?1. An exothermic reaction is spontaneous.2. If the number of moles o f gas does notchange in a chemical reaction, then ∆S0= 0.3. A reaction for which delta S0is positiveis spo ntaneous.4. If ∆H0and ∆S0are both positive, ∆G0will decrease as the temperature increases.011 10.0 pointsFor the reaction2 SO3(g) → 2 SO2(g) + O2(g)∆H◦r= +198 kJ · mol−1and ∆S◦r=190 J · K−1· mol−1at 298 K. The forwardreaction will be spontaneous atmcdonald (pam78654) – HW 6B: Thermodynamics – laude – (89 560) 31. temperatures above 104 2 K.2. all temperatures.3. temperatures above 131 5 K.4. temperatures below 1042 K.5. no temperature.012 10.0 pointsWhich of the following is not a definition o fenthalpy or change in enthalpy?1. A measure of the motional energy of asystem.2. A correction for internal energy that ac-counts for pressure-volume work.3. A measure of the heat of a system atconstant pressure.4. A measure of a system’s ability to changethe entropy of its surroundings.013 10.0 pointsWhich of the following quantities is not pathindependent?1. entropy (S)2. volume (V)3. pressure (P)4. heat (q)5. enthalpy (H)014 10.0 pointsWhich of the following would experi ence thesmallest increase in temperature if 1 kJ ofheat were added to it?1. 1 g of copper metal2. 10 g of water3. 10 g of copper metal4. 1 g of water015 10.0 pointsGiven the following data:3CO2(g) + 4H2O(l) ←→ C3H8(g) + 5O2(g)∆H = 1, 110 kJ · mol−1H2O(l) ←→ H2(g) + 1/2O2(g)∆H = 142.5 kJ · mol−13Cgraphite+ 4H2(g) ←→ C3H8(g)∆H = −52 kJ · mol−1calculate ∆H for the reactionCgraphite+ O2(g) ←→ CO2(g)1. −592 kJ · mol−12. −543 kJ · mol−13. −197 kJ · mol−14. 543 kJ · mol−15. 1202 kJ · mol−1016 10.0 pointsRank the following reactio ns from leastto greatest in terms of change in entropy(∆Srxn):a) KNO3(aq) + NaCl(a q)−→ NaNO3(aq) + KCl(aq)b) 4Ag(s) + O2(g) −→ 2Ag2O(s)c) 2H2O2(ℓ) −→ 2H2O(g) + O2(g)d) NaHCO3(s) −→ NaOH(s) + CO2(g)1. b < a < c < d2. a < b < d < c3. c < d < b < a4. b < a < d < cmcdonald (pam78654) – HW 6B: Thermodynamics – laude – (89 560) 45. a < d < b < c6. d < c < a < b017 10.0 pointsPhosphine (the common name for PH3, ahighly toxic gas used for fumigation), hasa ∆H◦vap= 14.6 kJ · mol−1and a S◦vap=78.83 J · mol−1· K−1. What is the normalboiling point of phosphine expressed in centi-grade?1. 185.2◦C2. −0.2◦C3. −87.8◦C4. 273◦C018 10.0 pointsWhich of the following combustion reac-tions does not occur at high temperature?I) C6H12O6(s) + 6O2(g)←→ 6CO2(g) + 6H2O(g)II) 2H2(g) + O2(g)←→ 2H2O(g)III) C3H8(g) + 5O2(g)←→ 3CO2(g) + 4H2O(g)1. II, III2. II only3. III only4. I, II5. I, II, III6. I, III7. I only019 10.0 points(For this problem assume that the calorime-ter itself absorbs no heat, the density of wateris 1.00 g · mL−1, and the specific heat capac-ity of water is 4.18 4 J · g−1· K−1.)1.14 g of octa ne (C8H18) is combusted in abomb calorimeter surrounded by 1 L of water.The initial and final temperatures of the waterare 25◦C and 38◦C respectively. Determinethe molar enthalpy of combustion of octane.1. −5, 440 kJ · mo l−12. −54, 400 kJ · mol−13. −54.4 kJ · mol−14. −544 kJ · mol−15. −5.44 kJ · mol−1020 10.0 pointsIf both ∆ngasand ∆n for a particular reac-tion are zero, which statement below would bethe most accurate prediction we could makeabout the change in entropy?1. It is definitely positive.2. It may be either positive or negative andis probably very small.3. It is definitely negative.4. It may be either positive or
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